When applying automatic speech recognition (ASR) to meeting recordings including spontaneous speech, the performance of ASR is greatly reduced by the overlap of speech events. In this paper, a method of separating the overlapping speech events using an adaptive beamforming (ABF) framework is proposed. The main feature of this method is that all the necessary information for the adaptation of ABF, including microphone calibration, is obtained from meeting recordings based on the results of speech event detection. The performance of the separation is evaluated via ASR using real meeting recordings.